The present invention relates to a conductive member to be mounted on the surface of a printed circuit board and pressed against a grounding conductor, thereby allowing electrical conduction between a circuit pattern on the printed circuit board and the grounding conductor.
There is a conventionally known technique in which a conductive member is mounted on the surface of a printed circuit board and, in that state, the printed circuit board is fixed in such a manner that the conductive member is pressed against a grounding conductor, such as a chassis or the like, thereby electrically connecting (grounding) a circuit pattern on the printed circuit board to the grounding conductor via the conductive member. Especially, in recent years, more and more instruments having microcomputers built therein have been being manufactured with the development of computer technology. Accordingly, the aforementioned technique is now indispensable for grounding printed circuit boards within such instruments.
An example of conductive members conventionally known is disclosed in the U.S. Pat. No. 3,504,095, which is illustrated in FIGS. 6A and 6B. As shown in FIG. 6A, this conductive member comprises a joint part 110 to be soldered to a circuit pattern 210 on a printed circuit board 200, a contact part 130 bent back from an end (shown by xcex1) of the joint part 110, and an extended part 132 further extended from the contact part 130 in the direction of the joint part 110.
This conductive member abuts on a grounding conductor 300 and is elastically deformed as shown in FIG. 6B. When the conductive member is elastically deformed, an edge 132a of the extended part 132 is moved on the printed circuit board 200 in the right direction. Also, with the elastic deformation of the conductive member, a top area of the contact part 130, which is shown by xcex2 in FIG. 6A, is also moved in the right direction, as shown in FIG. 6B.
Because of such structure, in the conductive member as disclosed in the U.S. Pat. No. 3,504,095, the edge 132a of the extended part 132 becomes an obstacle, and it is thus impossible to mount other components in the vicinity of the edge 132a. As a result, this type of conductive member is not usable on a densely integrated printed circuit board. Also, since a contact area between the grounding conductor 300 and the contact part 130 is relocated with the elastic deformation of the conductive member, it is difficult to maintain a desirable grounding condition. Furthermore, the length of the contact part 130 bent back from the end of the joint part 110 and that of the extended part 132 are too long, which may cause a lateral slippage of the contact part 130 and the extended part 132 when they are compressed.
The present invention was made to solve the aforementioned problems. More particularly, the object of the invention is to provide a conductive member which can be used on a densely integrated printed circuit board, with which a desirable grounding condition can be ensured, and in which slippage of a contact part can be prevented.
In order to attain the aforementioned object, there is provided a conductive member, made of a conductive and elastic thin sheet metal member, comprising a joint part having a joint surface to be soldered to a circuit pattern on a printed circuit board, an arm part bent back from an end of the joint part in the direction opposite to the joint surface, and a contact part further bent back from a vicinity of an end of the arm part, having a width narrower than that of the arm part, the conductive member being mounted on the printed circuit board for electrical connection between the circuit pattern and a grounding conductor, wherein a receiving hole capable of receiving at least a portion of the contact part is formed in the arm part so as to restrict slippage of the contact part within a predetermined range.
More specifically, in the conductive member of the invention, the arm part is bent back from the end of the joint part, and further, the contact part is bent back from the vicinity of the end of the arm part. Because of this structure, displacement of a contact area between the contact part and the grounding conductor is reduced at the time of elastic deformation of the contact part. As a result, a desirable grounding condition can be ensured. Also, the conductive member of the invention comprises no extended part, unlike the conventional conductive member as mentioned above, and it is thus usable on a densely integrated printed circuit board. Furthermore, since the contact part is received within the receiving hole of the arm part, slippage of the contact part is restricted within a predetermined range, by means of the arm part having a width wider than that of the contact part.
In the foregoing conductive member of the invention, at least a portion of the contact part is received within the receiving hole, thereby restricting slippage of the contact part within a predetermined range. The portion of the contact part may, of course, be received within the receiving hole only when the contact part is elastically deformed. Otherwise, the portion of the contact part may be received within the receiving hole even in a state in which the contact part is not elastically deformed.
In the foregoing conductive member of the invention, at least the contact part abuts on the grounding conductor, thereby elastically deforming the arm part as well as the contact part towards the joint part.
In the foregoing conductive member of the invention, the arm part also abuts on the grounding conductor, together with the contact part, when the arm part and the contact part are elastically deformed. In this case, a proper electrical conduction can be achieved between the grounding conductor and the circuit pattern on the printed circuit board.
The contact part and the receiving hole may be formed by cutting and raising a portion of the arm part. Alternatively, the contact part may be formed as an extension of the arm part and bent back from the end of the arm part.
It is possible to form an entire surface of the joint part as a joint surface. However, it is preferable that the joint part comprises a plurality of joint surfaces. In the case of a plurality of joint surfaces, a so-called self-alignment effect is available. The self-alignment effect is caused by surface tension of the melted solder. More specifically, when a conductive member disposed on the melted solder is out of position, force acts on the conductive member, by means of the surface tension of the melted solder, so as to replace it in position.
It is also preferable that the contact part comprises an attachment surface which can be grasped by a vacuum suction automatic mounting machine, by means of vacuum suction, such that the mounting operation of the conductive member onto the printed circuit board can be performed automatically. Further, in such a case, the attachment surface is preferably displaced, by elastic deformation of the arm part and the contact part, maintaining a substantially parallel relationship relative to the joint surface. In this manner, even if elastic deformation is caused by abutment on a vacuum suction nozzle of the vacuum suction automatic mounting machine, there are few gaps produced between the nozzle and the attachment surface. Consequently, the conductive member can be grasped efficiently, which results in the improvement of efficiency in the automatic mounting operation.